Stereochemistry of Carbenic 1,2-Vinyl Shifts

Article abstract of DOI:10.1021/jo971691t

Various 1-phenylbut-3-enylidenes, (Ph)CCR₂CH=CHR', were generated thermally and photolytically from tosylhydrazone (diazo) precursors. 1,2-Vinyl shifts, leading to 1,3-dienes, R′CH=CHC(Ph)=CR₂, were found to predominate over γ-C-H insertion (R = Me) and to compete with 1,2-H shifts (R = H). Intramolecular addition to the double bond was detected in the case of R = R′ = Me. The resulting bicyclobutane is thermally stable and does not mediate the vinyl shift. Stereospecific migration of 1-propenyl groups (R′ = Me), with retention of configuration, was observed on thermolysis and direct photolysis of appropriate substrates. These data exclude the intervention of a triplet diradical and point to vinyl migration in the singlet manifold. Benzophenone-sensitized generation of the carbenes led to partial stereomutation but did not provide conclusive evidence for a triplet rearrangement (isomerization of the diene products could not be avoided under these conditions).

Full text of DOI:10.1021/jo971691t

1178
J . Org. Chem. 1998, 63, 1178-1184
Ster eoch em istr y of Ca r ben ic 1,2-Vin yl Sh ifts
Wolfgang Kirmse* and Siegfried Kopannia
Fakulta¨t fu¨r Chemie, Ruhr-Universita¨t Bochum, D-44780 Bochum, Germany
Received September 9, 1997
Various 1-phenylbut-3-enylidenes, (Ph)CCR2CHdCHR′, were generated thermally and photolytically
from tosylhydrazone (diazo) precursors. 1,2-Vinyl shifts, leading to 1,3-dienes, R′CHdCHC(Ph)dCR2,
were found to predominate over γ-C-H insertion (R ) Me) and to compete with 1,2-H shifts (R )
H). Intramolecular addition to the double bond was detected in the case of R ) R′ ) Me. The
resulting bicyclobutane is thermally stable and does not mediate the vinyl shift. Stereospecific
migration of 1-propenyl groups (R′ ) Me), with retention of configuration, was observed on
thermolysis and direct photolysis of appropriate substrates. These data exclude the intervention
of a triplet diradical and point to vinyl migration in the singlet manifold. Benzophenone-sensitized
generation of the carbenes led to partial stereomutation but did not provide conclusive evidence
for a triplet rearrangement (isomerization of the diene products could not be avoided under these
conditions).
When carbenes are generated next to saturated carbon,
1,2-Vinyl migrations are close analogues of phenyl
shifts. Moreover, the stereoisomers (E/Z) of 1-alkenyl
groups can serve to probe the mechanism. In previous
sudies, vinyl shifts were induced by decomposition of the
diazo compounds 4 (R ) Ph, Me).6,7 Intramolecular C-H
insertion (f6) and, in the case of R ) Ph, addition to π
bonds were found to compete with vinyl migration (f5).
These reactions are not well-suited for mechanistic
analysis as the substrates 4 lack geometric isomerism,
and spin inversion of the intervening allylcarbenes is
presumed to be slow. In the present work, we focus on
analogues of 1 in which the migrating phenyl group was
replaced with 1-propenyl. We observe that 1,2-shifts of
(E)- and (Z)-1-propenyl groups to the divalent carbon
proceed with retention of configuration.
a 1,2-migration can take place with formation of an
alkene.1 Although the ease of shift can be influenced by
nonmigrating (“bystander”) substituents, the qualitative
ranking of inherent migratory ability appears to be H >
Ph > Me. 1,2-H shifts are generally accepted to proceed
from the singlet state but can occasionally be “mimicked”
by carbene precursors, such as (excited) diazo compounds
and diazirines.2 The multiplicity of aryl migrations is a
matter of dispute. The problem is particularly relevant
for arylcarbenes, such as 1, whose spin states equilibrate
rapidly. The Ph/H ratios, as reflected by the relative
yields of 2 and 3, tend to increase at low temperatures3
and to decrease on addition of methanol, a singlet
quencher.4 Both effects suggest that the phenyl group
can migrate in the triplet manifold. On the other hand,
donor substituents are known to promote aryl shifts.5
Electron-deficiency of the migrating aryl group points to
a dipolar rather than a diradical transition state.
Resu lts a n d Discu ssion
2,2-Dim eth yl-1-p h en yl-3-bu ten ylid en e (16). The
reactivity of carbenes tends to be lowered by π conjuga-
tion. Therefore, we had to make sure that vinyl groups
migrate to a phenyl-substituted terminus. As our first
model we chose 16. An indirect route to 16 was pursued
by Padwa et al., who studied the flash vacuum pyrolysis
(FVP) of the oxadiazolinone 7 at ca. 700 °C.8 Extrusion
of CO2 from 7 is thought to generate the diazo compound
13, either by a 3,3-sigmatropic shift of the nitrilimine 8
or via 9 (Scheme 1). Decomposition of 13, with interven-
(1) For reviews, see: (a) Nickon, A. Acc. Chem. Res 1993, 26, 84. (b)
Doyle, M. P. Chemistry of Diazirines; CRC Press: Boca Raton, FL,
1987; Chapter 8. (c) J ones, W. M. In Rearrangements in Ground and
Excited States; de Mayo, P., Ed.; Academic Press: New York, 1980;
Vol. 1, pp 95-160. (d) Schaefer, H. F., III Acc. Chem. Res. 1979, 12,
288. (e) Gaspar, P. P.; Hammond, G. S. In Carbenes; Moss, R. A., J ones,
M., J r., Eds.; Wiley: New York, 1975; Vol. II, pp 207-362. (f) Kirmse,
W. Carbene Chemistry, 2nd ed.; Academic Press: New York, 1971;
Chapter 12.
(2) (a) Modarelli, D. A.; Morgan, S.; Platz, M. S. J . Am. Chem. Soc.
1992, 114, 7034. (b) Fox, J . M.; Scacheri, J . E. G.; J ones, K. G. L.;
J ones, M., J r.; Shevlin, P. B.; Armstrong, N.; Sztyrbicka, R. Tetrahe-
dron Lett. 1992, 33, 5021. (c) Celebi, S.; Leyva, S.; Modarelli, D. A.;
Platz, M. S. J . Am. Chem. Soc. 1993, 115, 8613. (d) For a review, see:
Liu, M. T. H. Acc. Chem. Res. 1994, 27, 287. (e) For a computational
study, see: Miller, D. M.; Schreiner, P. R.; Schaefer, H. F., III J . Am.
Chem. Soc. 1995, 117, 4137.
(3) (a) Tomioka, H.; Ueda, H.; Kondo, S.; Izawa, Y. J . Am. Chem.
Soc. 1980, 102, 7817. (b) Tomioka, H.; Hayashi, N.; Izawa, Y.;
Senthilnathan, V. P.; Platz, M. S. J . Am. Chem. Soc. 1983, 105, 5053.
(4) Garcia-Garibay, M. A. J . Am. Chem. Soc. 1993, 115, 7011.
(5) (a) Kraska, A. R.; Chang, K.-T.; Chang, S.-J .; Moseley, C. G.;
Shechter, H. Tetrahedron Lett. 1982, 23, 1627. (b) Slack, W. E.; Taylor,
W.; Moseley, C. G.; Kraska, A.; Press, L. H.; Cherney, L.; Shechter, H.
Tetrahedron Lett. 1994, 35, 2647.
(6) Zimmerman, H. E.; Samuel, C. J . J . Am. Chem. Soc. 1975, 97,
4025.
(7) Kraska, A. R.; Cherney, L. I.; Shechter, H. Tetrahedron Lett.
1982, 23, 2163.
(8) (a) Padwa, A.; Caruso, T.; Nahm, S. J . Org. Chem. 1980, 45, 4065.
(b) Padwa, A.; Caruso, T.; Nahm, S.; Rodriguez, A. J . Am. Chem. Soc.
1982, 104, 2865.
S0022-3263(97)01691-5 CCC: $15.00 © 1998 American Chemical Society
Published on Web 01/23/1998

Stereochemistry of Carbenic 1,2-Vinyl Shifts
J . Org. Chem., Vol. 63, No. 4, 1998 1179
Sch em e 1
occurred in degassed solutions. Intramolecular reactions
of 16 prevail even in protic solvents; only a fraction of
the carbene is intercepted by O-H insertion. Somewhat
unexpectedly, the yield of 14 (in water) was inferior to
that of 15 (in methanol). Aqueous solutions of 12 became
turbid on photolysis as 13, and products derived there-
from were formed as a dispersed organic phase. The
heterogeneity of the aqueous medium impedes O-H
insertion, as compared with the homogeneous solution
in methanol.
In diglyme, benzophenone sensitization gave rise to 17
at the expense of 18. The triplet-induced transformation,
R2CN2 f R2CH2, does not necessarily involve a carbene
intermediate, as was discussed elsewhere.9 Moreover, 18
was converted into nonvolatile products (polymers?) when
irradiated in the presence of benzophenone. In view of
these side reactions, a comparison of direct and sensitized
photolyses of 12 in diglyme is not meaningful. In
contrast, the product distribution obtained from metha-
nolic solutions of 12 was but slightly affected by triplet
sensitization (Table 1). These data point to a spin-
equlibrated intermediate.
Conspicuously absent from the photolysis mixtures is
the product of intramolecular addition, 23. Since thermal
rearrangements of bicyclobutanes are known to give 1,3-
dienes,10 the question arises whether 18 could be formed
by way of 23. This route is inconsistent with the
properties of 23 which was reportedly distilled at 55 °C/3
Torr.11 Moreover, pyrolysis of the closely related 1,2,2-
trimethylbicyclo[1.1.0]butane (24) at 300 °C gave nearly
equimolar amounts of 25 (53%) and 26 (47%).12 The
phenyl analogue of 26, 4-methyl-2-phenyl-1,3-pentadiene,
was not obtained from photolyses of 2. Therefore, a direct
1,2-vinyl shift, 16 f 18, appears most likely.
Ta ble 1. P r od u cts fr om P h otolysesa of 12
yield
(%)
conditions
diglyme
diglyme, Ph2COb 10.2 28.2
18 cis-19 trans-19 14 15
17
43.6 34.6
21.8
18.1
26.2
20.4
17.1
70
18
30
50
2,2-Dim eth yl-1-p h en yl-3-p en ten ylid en e (33). Re-
peated alkylation of 1-phenyl-(E)-3-penten-1-one (E-27)
with MeI-LDA provided E-2813 (Scheme 2). The analo-
gous methylation of Z-27 could not be carried to comple-
tion, but Z-28 was isolated from the resulting mixture
by HPLC. While E-28 was smoothly converted into the
tosylhydrazone E-29, the forcing conditions required for
Z-28 led to partial Z f E isomerization (NMR). Attempts
to separate the product mixture failed. Therefore, our
studies were limited to the generation and reactions of
E-33.
Flash vacuum pyrolysis of the tosylhydrazone sodium
salt E-30 at ca. 280 °C gave equimolar amounts of the
bicyclobutane 35 (by intramolecular addition) and the
diene E-36 (by 1,2-vinyl shift). Photolyses of E-30 in
diglyme produced some cyclopropane 37 (by C-H inser-
tion) in addition to 35 and 36 (Table 2). When E-30 was
43.5
water
38.9 29.0
41.2 22.4
5.9
MeOH
16.0
MeOH, Ph2COb 42.6 25.6
14.7 trace 16
a
Pyrex vessel, medium presure mercury arc, 0.046 M 12, 20
b
°C, 30 min. 1.6 equiv, 0.073 M.
tion of the carbene 16, should lead to 18 (by 1,2-vinyl
shift) and 19 (by C-H insertion). The products actually
obtained on pyrolysis of 7 were 21 (45%) and 22 (25%).
Most likely, 21 arises from 18 by 1,5-H shift, and
vinylcyclopropane rearrangement of 19 affords 22.
Although the formation of 21 indicates that the vinyl
shift 16 f 18 does occur at high temperatures, less
vigorous conditions and a more straightforward approach
were desirable. Base-induced cleavage of the tosylhy-
drazone 11 provided pentane solutions of the diazo
compound 13, ν(N2) ) 2055 cm-1. When these solutions
were photolyzed, only 0.5% of 18 and 19 was formed.
Much better yields were obtained on photolysis of the
tosylhydrazone sodium salt 12 in diglyme (1,1′-oxybis[2-
methoxyethane]) (Table 1). On prolonged irradiation, 18
was converted into the oxirane 20. The apparent oxida-
tion was accelerated by the presence of oxygen but also
(9) Guth, M.; Kirmse, W. Acta Chem. Scand. 1992, 46, 606.
(10) For
a review, see: Gajewski, J . J . Hydrocarbon Thermal
Isomerizations; Academic Press: New York, 1981; p 45.
(11) Gollnick, K.; Weber, M. Tetrahedron Lett. 1990, 31, 4585.
(12) Skattebøl, L. Tetrahedron Lett. 1970, 2361.
(13) van der Weerdt, A. J . A.; Cerfontain, H. J . Chem. Soc., Perkin
Trans. 2 1980, 592.

1180 J . Org. Chem., Vol. 63, No. 4, 1998
Kirmse and Kopannia
Sch em e 2
minimized by low conversion and eliminated by irradia-
tion with light of g400 nm, using a NaNO2 filter (Table
4). Substantial Z f E isomerization of the 1,3-dienes
occurred in benzophenone-sensitized photolyses, whereas
41 and 43 were exclusively Z. These observations point
to the configurational integrity of the substrate. Controls
confirmed that the 1,3-dienes 44, 45, and 46 undergo
geometrical isomerization on direct (<400 nm) as well
as sensitized irradiation. Nevertheless, nonstereospecific
rearrangements of triplet 42 cannot be definitively
excluded.
Su m m a r y a n d Con clu sion
1,2-Vinyl shifts of 1-phenylbut-3-enylidenes (47), lead-
ing to 1,3-dienes (48), prevail over γ-C-H insertion (R )
Me) and compete with 1,2-H shifts (R ) H). Intramo-
lecular addition to the double bond occurs only in the case
of R ) R′ ) Me. The resulting bicyclobutane is thermally
stable and does not mediate the vinyl shift. Stereospe-
cific migration of 1-propenyl groups (R′ ) Me), with
retention of configuration, excludes an intermediate 49,
which is capable of rotation about the exocyclic C-C
bond. Such rotation would be anticipated if 49 were a
triplet diradical. Our data demonstrate that 1,2-vinyl
shifts do proceed in the singlet manifold. Therefore,
analogous phenyl shifts should not be dismissed a priori.
photolyzed in methanol, the ether 34 was also present
in the product mixture. Sensitization with benzophenone
seemingly enhances the yield of 34 at the expense of 35.
However, these changes are largely due to the fact that
the products decay at different rates, 35 > 36 > 34, on
benzophenone-sensitized irradiation (see Experimental
Section). Therefore, the quantitative results of sensitized
photolyses should be interpreted with caution. Although
E-36 prevailed in all reactions, minor amounts of Z-36
were also found, particularly in the presence of ben-
zophenone. The stereochemical “leakage” may be associ-
ated with the 1,2-vinyl shift, but light-induced E/Z
isomerization of substrate and/or product is also possible.
This point was not clarified, as the lack of pure Z
substrate precluded a complete stereochemical analysis.
A more significant result is the persistence of the bicy-
clobutane 35. The thermal stability of 35 suggests that
bicyclobutanes should have been detected if formed from
the carbenes 16 (above) and 42 (below).
1-P h en yl-3-p en ten ylid en e (42). 1,2-Hydrogen shifts
of carbenes1 and, in some cases, of carbene precursors2
proceed rapidly, often to the exclusion of competing
reactions. Therefore, our first choice for the present work
was 33 rather than 42. However, in view of our failure
to generate Z-33, we resorted to the parent system.
Fortunately, 42 was found to undergo the 1,2-vinyl shift
(f44), albeit to a lesser extent than 33 (Scheme 3).
The tosylhydrazones E-38 and Z-38 were described by
Padwa et al., who studied the intramolecular cycloaddi-
tion of the diazo compound 40 but did not explore the
carbenic reactivity.14 Flash vacuum pyrolysis of the
sodium salt E-39 afforded E-44 as well as E-45 and E-46
(Table 3). The double bond newly formed by 1,2-H shift
assumes both the E and Z geometry while the configu-
ration at C-4 is retained in all products. This does not
hold for photolyses of E-39, which gave rise to Z-45 and
Z-46 in addition to E-44, E-45, E-46, and, in methanol,
E-43. The Z-dienes were not detected at low conversions;
hence they are likely to arise by photoisomerization of
E-45 and E-46, respectively.
Exp er im en ta l Section
Gen er a l. Melting points were determined on a Kofler hot-
stage apparatus and are uncorrected. 1H NMR spectra were
recorded at 80 and/or 400 MHz. Chemical shifts (δ) are
reported as units (ppm) downfield from tetramethylsilane as
an internal standard. Gas chromatography (GC) was per-
formed on glass capillary columns of 0.25-0.38 mm diameter
(length, stationary phase, and temperature for the individual
mixtures are given below). Packed glass columns were used
for preparative gas chromatography (PGC). High-pressure
liquid chromatography (HPLC) was performed on stainless
steel columns 300 × 5 mm i.d. (analytical) and 300 × 25 mm
i.d. (preparative), employing refractometric detection. The
apparatus used for the flash vacuum pyrolysis of tosylhydra-
zone sodium salts (280-300 °C, 10-3 Torr) has been described
elsewhere.15 Photolyses were carried out using a 150-W
medium-pressure mercury arc lamp in a water-cooled Pyrex
immersion well (ca. 10 mm i.d.). In some experiments, 0.1 M
NaNO2 was circulated through the immersion well (λ g 400
nm).16 Pyrex cylindrical vessels or tubes containing the
samples were strapped around this well, and the assembly was
immersed in a water bath held at 20 °C.
P r ep a r a t ion of Tosylh yd r a zon e Sod iu m Sa lt s. To a
solution of the tosylhydrazone (1 mmol) in 5 mL of anhydrous
The thermolysis of Z-39 proceeded stereospecifically,
with exclusive formation of Z-44, Z-45, and Z-46. The
formation of E isomers on direct photolysis of Z-39 was
(15) (a) Brinker, U. H.; Ko¨nig, L. Chem. Ber. 1983, 116, 882. (b)
Kirmse, W.; Streu, J . Chem. Ber. 1984, 117, 3490.
(16) Murov, S. L. Handbook of Photochemistry; Dekker: New York,
1973; p 97.
(14) Padwa, A.; Rodriguez, A.; Tohidi, M.; Fukunaga, T. J . Am.
Chem. Soc. 1983, 105, 933.

Stereochemistry of Carbenic 1,2-Vinyl Shifts
J . Org. Chem., Vol. 63, No. 4, 1998 1181
Ta ble 2. P r od u cts Obta in ed fr om 30
37
conditions
E-31
E-34
35
E-36
Z-36
cis-E
cis-Z
trans-E
yield (%)
FVP,a 280 °C
50.7
41.1
39.6
37.5
5.9
49.3
47.5
44.7
41.6
43.1
66
74
16
64
15
hνb, diglyme
4.6
6.8
6.0
1.8
0.6
hνc, diglyme, 0.2 M Ph2CO
5.3
6.8
4.4
2.0
6.3
hνb, MeOH, 0.2 M NaOMe
11.8
33.6
1.6
1.5
3.7
2.2
hνc, MeOH, 0.2 M NaOMe, 0.4 M Ph2CO
a
b
Flash vacuum pyrolysis (10-3 Torr). 60 min. c 30 min.
prepared according to a published procedure.18 The products
obtained from thermolyzes and photolyes of 12 or 13 (for
reaction conditions, see Table 1) were analyzed by GC (18 m
OV17, 140 °C, and 30 m Marlophen, 110 °C) and separated
by HPLC (Si 60-5-C18, methanol-water ) 75:25). Yields were
estimated by GC, using dodecane as an internal standard
(Table 1). When 12 was photolyzed in diglyme, the epoxide
20 appeared after 60 min and increased to ca. 8% after 120
min. Saturation with oxygen promoted the formation of 20
(7% after 50 min, 10% after 90 min). Under these conditions,
20 was also formed by irradiation of 18.
Sch em e 3
The structures attributed to the reaction products were
corroborated by synthesis. Wolff-Kishner reduction of 10 (1,2-
ethanediol, 150 °C, 3 h) gave 3-methyl-4-phenyl-1-butene (17)19
1
(64%), H NMR (CDCl3) δ 1.0 (s, 6 H), 2.55 (s, 2 H), 4.9 (ddd,
J ) 17, 10, 1.5 Hz, 2 H), 5.9 (dd, J ) 17, 10 Hz, 1 H), 7.0-7.3
(m, 5 H). Dehydration of 4-methyl-3-phenyl-1-penten-3-ol20
(8.0 g, 45 mmol) with 0.8 g of 85% phosphoric acid (80 °C, 3 h)
afforded 4-methyl-3-phenyl-1,3-pentadiene21 (18, 15%) along
with 2-methyl-3-phenyl-1,3-pentadiene8 (21, 12%) and 3-iso-
propylindene22 (61%). The alkenes were separated by HPLC
(Si 60-5-C18, methanol-water ) 75:25). Oxidation of 18
(peracetic acid-sodium acetate in CH2Cl2, 20 °C, 16 h) gave
65% of 2,2-dimethyl-3-ethenyl-3-phenyloxirane (20): 1H NMR
(CDCl3) δ 1.0 (s, 3 H), 1.4 (s, 3 H), 5.2 (ddd, J ) 17, 11, 2 Hz,
2 H), 6.15 (dd, J ) 17, 11 Hz, 1 H), 7.2-7.4 (m, 5 H); 13C NMR
(CDCl3) δ 20.1 (CH3), 21.9 (CH3), 65.5 (C), 69.7 (C), 118.3 (CH2),
126.9 (CH), 127.1 (CH), 128.0 (CH), 136.5 (CH), 138.8 (C).
1-Ethenyl-1-methyl-2-phenylcyclopropane (19, E,Z mixture)
was obtained by benzylidene transfer to isoprene.23 Since
separation of the isomers on a preparative scale failed, trans-
(1-methyl-2-phenylcyclopropyl)methanol (trans-50)24 was oxi-
dized (MnO2, benzene, 45 h reflux) to the analogous aldehyde
51 which was converted into trans-19 by methylenation
(Ph3PCH3Br, NaH, DMSO, 90 °C, 2 h). The cis/trans assign-
ment of 19 by NMR23 was thus confirmed.
Ta ble 3. P r od u cts Obta in ed fr om E-39
yield
E-41 E-43 E-44 E-45 Z-45 E-46 Z-46 (%)
conditions
FVP,a 280 °C
hν, diglyme
hν, diglyme,
t f 0
32.1 52.4 15.5 72
10.1 45.1 6.1 27.1 11.6 68
8.0 57.9 34.1
hν, diglyme,
0.4 M Ph2CO
hν, MeOHb
hν, MeOH,b
0.2 M Ph2CO
hν, MeOH,b
0.4 M Ph2CO
10.1
7.2 47.5 12.3 16.7 6.2 17
11.3 13.1 50.0 3.0 21.4 1.2 49
4.6 26.5 14.8 31.0 9.4 9.9 3.8 25
4.3 30.9 15.3 24.9 9.1 10.5 5.0 17
a
b
Flash vacuum pyrolysis (10-3 Torr). 0.2 M NaOMe.
THF was added 1 mmol of sodium hydride (as a suspension
in mineral oil). The mixture was stirred for 30 min at room
temperature, n-pentane (40-50 mL) was added, and stirring
was continued for 30 min. The precipitated sodium salt was
filtered with suction, washed with n-pentane, and dried in
vacuo. If the sodium salt failed to crystallize, the solvent was
removed in vacuo, and the residue was triturated with pentane
in an ultrasound bath. Moisture and light should be excluded
during these processes.
2,2-Dim eth yl-1-ph en ylbu t-3-en -1-ol (14) an d 3,3-Dim eth -
yl-4-m eth oxy-4-p h en ylbu ten e (15). To a solution of 10 (0.80
g, 4.6 mmol) in ether (10 mL) was added a solution of NaBH4
(0.35 g, 9.2 mmol) in 0.1 N NaOH (5 mL). After the biphasic
mixture was stirred vigorously for 16 h, the phases were
separated. The ether solution was washed with water, dried
(MgSO4), and concentrated in vacuo to give 0.62 g (76%) of
crude (GC: 91%) 14, which was purified by PGC (0.5 m OV101,
100 °C): 1H NMR (CDCl3) δ 0.95 (s, 3 H), 1.0 (s, 3 H), 4.45 (d,
J ) 3 Hz, 1 H), 5.05 (ddd, J ) 17, 11, 1.5 Hz, 2 H), 5.9 (dd, J
2,2-Dim eth yl-1-p h en ylbu t-3-en -1-on e Tosylh yd r a zon e
(11). To a solution of p-toluenesulfonylhydrazine (11.4 g, 60
mmol) in methanol (50 mL) was added 2,2-dimethyl-1-phen-
ylbut-3-en-1-one (10)17 (10.2 g, 60 mmol). After the mixture
was heated at reflux for 1 h, it was allowed to stand at room
temperature for 48 h. The precipitate was filtered off and
recrystallized from ethanol to give 12.9 g (63%) of 11: mp 105
°C; 1H NMR (CDCl3) δ 1.2 (s, 6 H), 2.45 (s, 3 H), 4.9 (ddd, J )
17, 11, 1 Hz, 2 H), 5.75 (dd, J ) 17, 11 Hz, 1 H), 6.7-7.0 (m,
4 H), 7.2-7.4 (m, 3 H), 7.7-7.9 (m, 2 H). Anal. Calcd for
(18) J onczyk, A.; Wlostowska, J . Synth. Commun. 1978, 8, 569.
(19) Shepherd, J r., L. H. (Ethyl Corp.) U.S. Patent 3,670,001 (J une
13, 1972); Chem. Abstr. 1972, 77, 114553.
(20) Colonge, J .; Brunie, J .-C. Bull. Soc. Chim. Fr. 1963, 42.
(21) Tzeng, D.; Fong, R. H.; Soysa, H. S. D.; Weber, W. P. J .
Organomet. Chem. 1981, 219, 153.
(22) Weidler, A. M. Acta Chem. Scand. 1963, 17, 2724.
(23) Fischer, H.; Hofmann, J . Chem. Ber. 1991, 124, 981.
(24) (a) To¨mo¨sko¨zi, I. Tetrahedron 1966, 22, 197. (b) Schultz, A. L.
J . Org. Chem. 1971, 36, 383.
C
19H22N2O2S: C, 66.67; H, 6.43; N, 8.19. Found: C, 66.59; H,
6.49; N, 8.22.
Rea ction P r od u cts of 2,2-Dim eth yl-1-p h en yl-3-bu ten -
ylid en e (16). Solutions of the diazo compound 13 were
(17) Rousseau, G.; Conia, J . M. Tetrahedron Lett. 1981, 22, 649.

1182 J . Org. Chem., Vol. 63, No. 4, 1998
Ta ble 4. P r od u cts Obta in ed fr om Z-39
Kirmse and Kopannia
conditions
FVP,a 280 °C
Z-41
Z-43
E-44
Z-44
E-45
Z-45
E-46
Z-46
yield (%)
34.5
10.1
7.9
8.9
4.7
12.2
8.7
7.3
43.1
28.5
66.4
73.1
33.1
52.8
41.8
39.2
22.4
18.2
23.5
18.0
18.6
17.1
8.3
69
69
hν, diglyme
5.7
trace
21.1
trace
16.4
2.2
hν, diglyme, t f 0
hν, diglyme, g400 nmb
hν, diglyme, 0.4 M Ph2CO
hν, MeOHc
18.3
1.5
15.6
5.3
8.3
8.2
1.3
1.6
3.0
17
80
37
23
11.3
23.7
21.1
hν, MeOH,c 0.2 M Ph2CO
hν, MeOH,c 0.4 M Ph2CO
1.1
1.7
6.5
6.9
10.5
10.3
a
b
Flash vacuum pyrolysis (10-3 Torr). Filtered with 0.1 M NaNO2. c 0.2 M NaOMe.
) 17, 11 Hz, 1 H), 7.2-7.3 (m, 5 H). Anal. Calcd for
12H16O: C, 81.82; H, 9.09. Found: C, 81.91; H, 9.16. The
2,2-Dim eth yl-1-p h en yl-3-p en ten -1-on e Tosylh yd r a zon e
(29). Following a method similar to the preparation of 11,
2,2-dimethyl-1-phenyl-(E)-4-penten-1-one (28)13 (2.5 g, 13.3
mmol) and p-toluenesulfonylhydrazine (2.5 g, 13.5 mmol)
afforded 3.1 g (65%) of (E)-29: mp 104 °C; 1H NMR (CDCl3) δ
1.1 (s, 6 H), 1.5 (dd, J ) 6, 1 Hz, 3 H), 2.4 (s, 3 H), 5.15 (dq, J
) 16, 6 Hz, 1 H), 5.25 (dq, J ) 16, 1 Hz, 1 H), 6.7-7.8 (m, 9
H). Anal. Calcd for C20H24N2O2S: C, 67.39; H, 6.79; N, 7.86.
Found: C, 67.38; H, 6.77; N, 7.92.
C
alcohol 10 was previously obtained from a Wittig rearrange-
ment but no analytical data were reported.25
To a suspension of pentane-washed NaH (40 mg, 1.6 mmol)
in anhydrous THF (10 mL) was added 14 (0.18 g, 1 mmol).
The mixture was heated at reflux for 30 min. Methyl iodide
(0.30 g, 2.1 mmol) was then added, and heating at reflux was
continued for 30 min. The mixture was partitioned between
water and ether. The combined ether solutions were dried
(MgSO4) and concentrated in vacuo to give 0.17 g (73%) of 15
which was purified by PGC (0.5 m OV101, 100 °C): 1H NMR
(CDCl3) δ 0.95 (s, 3 H), 1.0 (s, 3 H), 3.15 (s, 3 H), 4.9 (ddd, J
) 17, 11, 1.5 Hz, 2 H), 5.9 (dd, J ) 17, 11 Hz, 1 H), 7.1-7.35
(m, 5 H). Anal. Calcd for C13H18O: C, 82.11; H, 9.47.
Found: C, 82.02; H, 9.55.
3-Meth yl-4-p h en yl-1,3-p en ta d ien e (54). The diene 54
was of interest as the product resulting from a 1,2-methyl shift
of the carbene 16. Freshly prepared MnO2‚H2O (3.9 g, 40
mmol) was dehydrated by azeotropic distillation with benzene
(70 mL). 2-Methyl-3-phenyl-2-buten-1-ol (52)26 (E,Z mixture,
1.6 g, 10 mmol) was then added. Azeotropic distillation of the
nitrogen-blanketed mixture was continued for 45 h while
progress of the reaction was monitored by GC. After being
cooled to room temperature, the benzene solution was filtered,
dried (MgSO4), and concentrated to give 1.5 g (95%) of crude
2-methyl-3-phenyl-2-butenal (53, E:Z ) 3:1): IR (CDCl3) 1670
cm-1 (CdO); 1H NMR (CDCl3) δ 1.65 (q, J ) 1 Hz, 0.75 H), 1.9
(q, J ) 1 Hz, 2.25 H), 2.25 (q, J ) 1 Hz, 2.25 H), 2.45 (q, J )
1 Hz, 0.75 H), 7.0-7.5 (m, 5 H), 9.45 (s, 0.75 H), 10.3 (s, 0.25
H).
A flask was charged with diisopropylamine (3.55 g, 35
mmol), HMPT (6.25 g, 35 mmol), and THF (25 mL) under
nitrogen. To the stirred solution was added at 0 °C n-
butyllithium (1.6 M in hexane, 21.9 mL, 35 mmol). The
mixture was stirred at 0 °C for 30 min and was then cooled to
-65 °C. A solution of 1-phenyl-(Z)-3-penten-1-one (Z-27)14 (3.0
g, 18.8 mmol) in THF (5 mL) was added, and stirring was
continued at -65 °C for 30 min. After the mixture was allowed
to warm slowly to 0 °C, a solution of methyl iodide (11.4 g, 80
mmol) in THF (10 mL) was added. The reaction mixture was
stirred for an additional 2 h at 0 °C and was then partititoned
between ether and water. The combined ether solutions were
washed with water, dried (MgSO4), and concentrated to give
2.7 g of a product mixture (1:1 by GC). Separation by HPLC
(Si 60-5-C18, methanol-water ) 4:1) afforded 1.1 g (34%) of
2-methyl-1-phenyl-(Z)-3-penten-1-one [IR (CDCl3) 1690 cm-1
(CdO); 1H NMR (CDCl3) δ 1.25 (d, J ) 7 Hz, 3 H), 1.75 (dd, J
) 6.5, 1.5 Hz, 3 H), 4.4 (dq, J ) 9, 7 Hz, 1 H), 5.5 (ddq, J ) 11,
9, 1.5 Hz, 1 H), 5.55 (dqd, J ) 11, 6.5, 0.5 Hz, 1 H), 7.4-7.6
(m, 3 H), 7.9-8.0 (m, 2 H)] and 1.2 g (35%) of 2,2-dimethyl-
1-phenyl-(Z)-3-penten-1-one (Z-28) [IR (CDCl3) 1680 cm-1
(CdO); 1H NMR (CDCl3) δ 1.35 (dd, J ) 7, 1.5 Hz, 3 H), 1.4 (s,
6 H), 5.45 (dq, J ) 11, 7 Hz, 1 H), 5.8 (dq, J ) 11, 1.5 Hz, 1
H), 7.3-7.5 (m, 3 H), 8.0-8.1 (m, 2 H)].
To a solution of p-toluenesulfonylhydrazine (0.8 g, 4.4 mmol)
in 0.05 M HCl-MeOH (10 mL) was added Z-28 (0.8 g, 43
mmol). After heating at reflux for 2 h, the dark mixture was
partitioned between ether and water. The combined ether
solutions were dried (MgSO4) and concentrated in vacuo.
HPLC (Si 60-5-C18, methanol-water ) 4:1) gave 0.6 g of
unreacted ketone and 15 mg (1%) of a mixture (ca. 1:1) of E-
and Z-29: 1H NMR (CDCl3) δ 1.1 (s, 3 H), 1.2 (s, 3 H), 1.25
(dd, J ) 7, 1.5 Hz, 1.5 H), 1.5 (dd, J ) 6, 1 Hz, 1.5 H), 2.38 (s,
1.5 H), 2.4 (s, 1.5 H), 5.1 (dq, J ) 11, 1.5 Hz, 0.5 H), 5.15 (dq,
J ) 16, 6 Hz, 0.5 H), 5.25 (dq, J ) 16, 1 Hz, 0.5 H), 5.35 (dq,
J ) 11, 7 Hz, 0.5 H), 6.7-7.8 (m, 9 H). Attempts to separate
the mixture failed, as did attempts to react Z-28 under less
forcing conditions.
R ea ct ion P r od u ct s of 2,2-Dim et h yl-1-p h en yl-(E)-3-
p en ten ylid en e (33). The reaction products obtained from
thermolyses and photolyses of 29 were analyzed by GC (37 m
OV17, 140 °C, and 28.5 m Marlophen, 140 °C). Yields were
estimated with dodecane as an internal standard (Table 2).
Prolonged direct irradiation (up to 2 h) had no significant effect
on product distributions. Triplet sensitization, however, led
to substantial changes which were mimicked by controls. Thus
the bicyclobutane 35 decayed rapidly (15 min, 56.5%; 30 min,
75.8%; 60 min, 93.3%), without formation of volatile products,
when irradiated in MeOH, 0.2 M NaOMe, 0.4 M Ph2CO.
Under similar conditions, 30% of the diene 36 was lost after
30 min and a E:Z ratio of ca. 3 was established. No significant
decay (30 min, <5%) and E/Z isomerization of the ether 34
To anhydrous DMSO (10 mL) was added sodium hydride
(60% in mineral oil, 0.4 g, 10 mmol). The mixture was heated
under nitrogen at 80 °C for 45 min and then cooled to 0 °C. A
solution of methyltriphenylphosphonium bromide (3.6 g, 10
mmol) in DMSO (20 mL) was added. After the mixture was
stirred at 0 °C for 10 min, 53 (1.5 g, 9.5 mmol) was added.
The solution was heated at 90 °C for 2 h and was then
partitioned between water and pentane. The combined pen-
tane extracts were washed with water, dried (MgSO4), and
concentrated in vacuo to give 1.4 g (93%) of 54, E:Z ) 71:29
(GC), which was purified by PGC (1.5 m OV101, 100 °C): 1H
NMR (CDCl3) δ 1.75 (q, J ) 1.5 Hz, 0.9 H), 2.0 (q, J ) 1.5 Hz,
2.1 H), 2.15 (q, J ) 1.5 Hz, 2.1 H), 2.2 (q, J ) 1.5 Hz, 0.9 H),
5.1 (ddd, J ) 17, 11, 1 Hz, 2 H), 6.55 (dd, J ) 17, 11 Hz, 1 H),
7.0-7.5 (m, 5 H). Anal. Calcd for C12H14: C, 91.14; H, 8.86.
Found: C, 91.00; H, 8.94. By means of this sample, the
presence of 54 among the reaction products of 16 was
definitively excluded.
(25) Baldwin, J . E.; DeBernardis, J .; Patrick, J . E. Tetrahedron Lett.
1970, 353.
(26) Shono, T.; Nishiguchi, I.; Komamura, T.; Fujita, K. Tetrahedron
Lett. 1977, 4327.

Stereochemistry of Carbenic 1,2-Vinyl Shifts
J . Org. Chem., Vol. 63, No. 4, 1998 1183
were observed. The products were identified by comparison
with samples from appropriate syntheses. The preparation
of 1-phenyl-2,2,exo-4-trimethylbicyclo[1.1.0]butane (35) [1H
NMR (CDCl3) δ 0.88 (d, J ) 6 Hz, 3 H), 0.90 (s, 3 H), 0.95 (s,
3 H), 1.6 (br s, 1 H), 1.9 (br q, J ) 6 Hz, 1 H), 7.15-7.25 (m,
5 H)] has been reported.26 For the remaining products, see
below.
methylindene (57, 56%) have been reported.22 Analogous
treatment of (Z)-55 gave a similar product mixture; (Z)-36 was
not obtained.
4,4-Dim et h yl-5-p h en yl-2-p en t en e (31). Following a
method similar to the preparation of 54, the ylide derived from
ethyltriphenylphosphonium iodide (2.5 g, 6.2 mmol) and NaH
(60%, 0.25 g, 62 mmol) in DMSO (5 mL) reacted with
2,2-dimethyl-3-phenylpropanal27 (0.5 g, 3.1 mmol) to give 0.4
g (80%) of crude 31, E:Z ) 3:7. The mixture was separated
by PGC (3 m Apiezon, 150 °C). E-31: 1H NMR (CDCl3) δ 0.95
(s, 6 H), 1.65 (dd, J ) 6.5, 1.5 Hz, 3 H), 2.55 (s, 2 H), 5.2 (dq,
J ) 16, 6.5 Hz, 1 H), 5.45 (dq, J ) 16, 1.5 Hz, 1 H), 7.05-7.25
(m, 5 H). Z-31: 1H NMR (CDCl3) δ 1.1 (s, 6 H), 1.62 (dd, J )
7, 1.5 Hz, 3 H), 2.65 (s, 2 H), 5.2 (dq, J ) 12, 7 Hz, 1 H), 5.45
(dq, J ) 12, 1.5 Hz, 1 H), 7.1-7.25 (m, 5 H). Anal. Calcd for
To a stirred, nitrogen-blanketed solution of 1-bromo-2-
methyl-1-phenylpropene (58)28 (4.0 g, 19 mmol) in ether (20
mL) was added at -78 °C n-butyllithium (1.6 M in ether, 40
mL, 64 mmol). After the mixture was allowed to warm to room
temperature, stirring was continued for 5 h. A solution of
N-formylpiperidine (2.5 g, 22 mmol) in ether (10 mL) was then
added, and the reaction was allowed to proceed for 2 h at room
temperature. The mixture was poured into ice water, and the
phases were separated. The aqueous phase was extracted with
ether (50 mL). The combined ether solutions were dried
(MgSO4) and concentrated in vacuo. Chromatography (silica
gel, ether-hexane ) 1:1) of the residue afforded 0.22 g (6.2%)
of 2-methyl-3-phenyl-2-heptene (59): [1H NMR (CDCl3) δ 0.8-
1.4 (m, 7 H), 1.6 (s, 3 H), 1.8 (s, 3 H), 2.3 (t, J ) 6 Hz, 2 H),
7.0-7.4 (m, 5 H)] and 1.98 g (65%) of 3-methyl-2-phenyl-2-
C
13H18: C, 89.59; H, 10.41. Found: C, 89.48; H, 10.33.
4,4-Dim eth yl-5-m eth oxy-5-p h en yl-(E)-2-p en ten e (E-34).
To a stirred, refluxing solution of E-28 (0.6 g, 3.2 mmol) in
methanol (5 mL) was added NaBH4 (0.25 g, 6.6 mmol). After
cooling to room temperature over 4 h, the mixture was
partitioned between water and pentane. The combined pen-
tane solutions were dried (MgSO4) and concentrated in vacuo.
GC indicated a 1:1 mixture of ketone and alcohol which was
separated by HPLC (Si-60-5, ether-hexane ) 1:1). 2,2-Di-
methyl-1-phenyl-(E)-3-penten-1-ol: 1H NMR (CDCl3) δ 0.9 (s,
3 H), 0.95 (s, 3 H), 1.7 (br d, J ) 7 Hz, 3 H), 4.4 (m, 1 H),
5.3-5.6 (m, 2 H), 7.3 (br s, 5 H). Anal. Calcd for C13H18O: C,
82.06; H, 9.53. Found: C, 82.05; H, 9.52.
1
butenal (60) [IR (CDCl3) 1670 cm-1 (CdO); H NMR (CDCl3)
δ 1.8 (s, 3 H), 2.35 (s, 3 H), 6.9-7.1 (m, 2 H), 7.3-7.4 (m, 3 H),
10.25 (s, 1 H)].
Following the procedure described for 15, 2,2-dimethyl-1-
phenyl-(E)-3-penten-1-ol (0.19 g, 1.0 mmol) was treated with
NaH (50 mg, 2.1 mmol) and methyl iodide (0.6 g, 4 mmol) to
give 0.19 g (93%) of 34: 1H NMR (CDCl3) δ 0.9 (s, 3 H), 0.95
(s, 3 H), 1.65 (d, J ) 6 Hz, 3 H), 3.15 (s, 3 H), 3.8 (s, 1 H),
5.0-5.7 (m, 2 H), 7.1-7.35 (m, 5 H). Anal. Calcd for
To a suspension of sodium amide (0.25 g, 6.2 mmol) in ether
(20 mL) was added ethyltriphenylphosphonium iodide (2.5 g,
6.2 mmol). The mixture was heated at reflux for 24 h.
A
C
14H20O: C, 82.30; H, 9.87. Found: C, 82.38; H, 9.80.
solution of 60 (0.5 g, 3.1 mmol) in ether (5 mL) was then added,
and heating at reflux was continued for 2 h. The solution was
filtered and concentrated in vacuo to give 0.4 g (75%) of 36,
E:Z ) 1:4. The mixture was purified by PGC (1 m DC200,
140 °C), which did not separate the isomers. Z-36: 1H NMR
(CDCl3) δ 1.4 (dd, J ) 7, 1.5 Hz, 3 H), 1.5 (s, 3 H), 1.7 (s, 3 H),
5.5 (dq, J ) 11, 7 Hz, 1 H), 6.1 (dq, J ) 11, 1.5 Hz, 1 H), 7.0-
7.35 (m, 5 H). Anal. Calcd for C13H16: C, 90.64; H, 9.36.
Found: C, 90.44; H, 9.24.
2-Meth yl-3-p h en yl-2,4-h exa d ien e (36). To a solution of
1-propenylmagnesium bromide, prepared from magnesium (3.7
g, 0.12 mol) and 1-bromopropene (18.1 g, 0.15 mol) in THF
(160 mL), was added a solution of isobutyrophenone (18.0 g,
0.12 mol) in THF (30 mL). The mixture was heated at reflux
for 2 h. Conventional workup afforded 18.0 g (79%) of
2-methyl-3-phenyl-4-hexen-3-ol (55) whose E,Z isomers (1:3,
GC) were separated by chromatography (silica gel, hexane-
ether ) 4:1). Z-55: 1H NMR (CDCl3) δ 0.8 (d, J ) 7 Hz, 3 H),
0.95 (d, J ) 7 Hz, 3 H), 1.6 (dd, J ) 7, 1 Hz, 3 H), 2.1 (sept, J
) 7 Hz, 1 H), 5.65 (dq, J ) 11, 7 Hz, 1 H), 6.0 (dq, J ) 11, 1
Hz, 1 H), 7.1-7.55 (m, 5 H). E-55: 1H NMR (CDCl3) δ 0.75
(d, J ) 7 Hz, 3 H), 0.9 (d, J ) 7 Hz, 3 H), 1.75 (dd, J ) 7, 1 Hz,
3 H), 2.15 (sept, J ) 7 Hz, 1 H), 5.3-6.1 (m, 2 H), 7.1-7.55
(m, 5 H). Anal. Calcd for C13H18O: C, 82.06; H, 9.53.
Found: C, 82.01; H, 9.53.
To (E)-55 (3.0 g, 15.8 mmol) was added 0.5 g of 85%
phosphoric acid. After the mixture was heated at 80 °C for 2
h, it was partitioned between pentane and water. The pentane
solutions were dried (MgSO4) and concentrated to give 2.0 g
(74%) of a product mixture which was separated by PGC (2.5
m Apiezon, 160 °C). 5-Methyl-4-phenyl-1,3-hexadiene (56,
18%): 1H NMR (CDCl3) δ 1.05 (d, J ) 7 Hz, 6 H), 2.7 (sept, J
) 7 Hz, 1 H), 4.8-5.3 (m, 2 H), 5.95-6.3 (m, 2 H), 7.0-7.5 (m,
5 H). 2-Methyl-3-phenyl-2,4(E)-hexadiene (E-36, 26%): 1H
NMR (CDCl3) δ 1.55 (s, 3 H), 1.7 (dd, J ) 7, 1 Hz, 3 H), 1.95
(s, 3 H), 5.0 (dq, J ) 16, 7 Hz, 1 H), 6.65 (dq, J ) 16, 1 Hz, 1
H), 7.0-7.5 (m, 5 H). Anal. Calcd for C13H16: C, 90.64; H,
9.36. Found: C, 90.53; H, 9.43. Data for 3-isopropyl-1-
1-Meth yl-2-p h en yl-1-(1-p r op en yl)cyclop r op a n es (37).
Using the same procedure for the synthesis of trans-1-methyl-
2-phenylcyclopropanemethanol (trans-50),24 ethyl cis-1-methyl-
2-phenylcyclopropanecarboxylate24b was reduced to give 90%
of cis-50: 1H NMR (CDCl3) δ 0.7-1.2 (m, 2 H), 1.35 (s, 3 H),
2.05 (dd, J ) 9, 7 Hz, 1 H), 3.25 (m, 2 H), 7.1-7.3 (m, 5 H).
Following a method similar to the preparation of 53, oxidation
of the alcohols with MnO2 (benzene, reflux) afforded the
corresponding aldehydes (91-95%). trans-1-Methyl-2-phenyl-
cyclopropanecarboxaldehyde (trans-51): IR (CDCl3) 1690 cm-1
(CdO), 1H NMR (CDCl3) δ 0.95 (s, 3 H), 1.4-1.7 (m, 2 H), 2.55
(dd, J ) 9, 7 Hz, 1 H), 7.1-7.3 (m, 5 H), 8.95 (s, 1 H). cis-1-
Methyl-2-phenylcyclopropanecarboxaldehyde (cis-51):29: IR
1
(CDCl3) 1690 cm-1 (CdO); H NMR (CDCl3) δ 1.35 (s, 3 H),
1.4-1.7 (m, 2 H), 2.55 (dd, J ) 9, 7 Hz, 1 H), 7.1-7.3 (m, 5 H),
8.55 (s, 1 H). Wittig reaction of trans-51 with ethyltriphen-
ylphosphonium iodide-NaH-DMSO (see preparation of 54)
afforded predominantly (E:Z ) 1.8, 75%) trans-1-methyl-2-
1
phenyl-1-[(E)-1-propenyl]cyclopropane (trans-E-37); H NMR
(CDCl3) δ 0.95 (s, 3 H), 1.1 (d, J ) 7 Hz, 2 H), 1.85 (d, J ) 5
Hz, 3 H), 2.1 (t, J ) 7 Hz, 1 H), 5.0-5.8 (m, 2 H), 7.1-7.4 (m,
5 H). The Wittig reaction of trans-51 with ethyltriphenylphos-
phonium iodide-NaNH2-ether (see preparation of Z-36) gave
predominantly (E:Z ) 0.2, 83%) trans-1-methyl-2-phenyl-1-
[(Z)-1-propenyl]cyclopropane (trans-Z-37); 1H NMR (CDCl3) δ
0.9 (s, 3 H), 1.0 (dd, J ) 6.5, 3.5 Hz, 1 H), 1.05 (dd, J ) 8.5,
3.5 Hz, 1 H), 1.8 (dd, J ) 7, 1.5 Hz, 3 H), 2.1 (dd, J ) 8.5, 6.5
(27) (a) Artaud, I.; Torossian, G.; Viout, P. Tetrahedron 1985, 41,
5031. (b) Stork, G.; Dowd, S. R. Org. Synth. 1988, Collect. Vol. VI,
526.
(28) Knorr, R.; Lattke, E. Chem. Ber. 1981, 114, 2116.
(29) (a) Scribe, P.; Monot, R. M.; Wiemann, J . Tetrahedron Lett.
1967, 5157. (b) Scribe, P.; Wiemann, J . Bull. Soc. Chim. Fr. 1971, 2268.

1184 J . Org. Chem., Vol. 63, No. 4, 1998
Kirmse and Kopannia
Hz, 1 H), 5.45 (dq, J ) 11, 7 Hz, 1 H), 5.65 (dq, J ) 11, 1.5 Hz,
1 H), 7.15-7.3 (m, 5 H). Anal. Calcd for C13H16: C, 90.64; H,
9.36. Found: C, 90.63; H, 9.37. Analogous reactions of cis-
51 afforded cis-E-37 (E:Z ) 5.0, 70%) and cis-Z-37 (E:Z < 0.01,
75%), respectively. cis-E-37: 1H NMR (CDCl3) δ 1.15 (d, J )
7 Hz, 2 H), 1.32 (s, 3 H), 1.67 (d, J ) 7 Hz, 3 H), 1.95 (t, J )
7 Hz, 1 H), 5.0-5.7 (m, 2 H), 7.0-7.3 (m, 5 H). Anal. Calcd
for C13H16: C, 90.64; H, 9.36. Found: C, 90.63; H, 9.44. cis-
Z-37: 1H NMR (CDCl3) δ 0.9-1.05 (m, 1 H), 1.1-1.2 (m, 1 H),
1.3 (s, 3 H), 1.65 (dd, J ) 7, 1.5 Hz, 3 H), 1.9 (m, 1 H), 5.15
(dq, J ) 11, 1.5 Hz, 1 H), 5.45 (dq, J ) 11, 7 Hz, 1 H), 7.0-7.3
(m, 5 H).
Rea ction P r od u cts of 1-P h en yl-3-p en ten ylid en e (42).
The tosylhydrazones E-38 and Z-3814 were converted into the
sodium salts E-39 and Z-39, respectively, according to the
general procedure. The products obtained on pyrolysis and
photolysis of 39 were analyzed by GC (60 m Marlophen, 130
°C); yields were estimated with 1-phenyl-2-butene as an
internal standard (Tables 3 and 4). The pyrolysis mixtures
were also separated by HPLC (Si-50-5-NO2, hexane). Controls
revealed Z/E isomerization of the dienes 44-46 on both direct
and sensitized irradiation in diglyme. No significant isomer-
ization occurred when the light was filtered with aqueous 0.1
M NaNO2.
1.55 (d, J ) 7 Hz, 3 H), 2.25-2.5 (m, 2 H), 3.02 (s, 3 H), 4.05
(t, J ) 6.5 Hz, 1 H), 5.3-5.5 (m, 2 H), 7.2-7.3 (m, 5 H). Anal.
Calcd for C12H16O: C, 81.78; H, 9.15. Found: C, 81.66; H, 9.12.
Z-43: 1H NMR (CDCl3) δ 1.45 (d, J ) 7 Hz, 3 H), 2.3-2.6 (m,
2 H), 3.2 (s, 3 H), 4.1 (t, J ) 7 Hz, 1 H), 5.3-5.5 (m, 2 H),
7.2-7.3 (m, 5 H). Anal. Calcd for C12H16O: C, 81.78; H, 9.15.
Found: C, 81.87; H, 9.12. Previous approaches led to 43 of
unspecified configuration.33
The NMR spectra of (E)- and (Z)-2-phenyl-1,3-pentadiene
(44) were in accordance with those reported.34 The reaction
of MeCHdCHCHdPPh3 with benzaldehyde35 afforded a mix-
ture of 1-phenyl-1,3-pentadienes which was separated by PGC
(4.5 m Apiezon, 150 °C). E-45: 1H NMR (CDCl3) δ 1.85 (dd,
J ) 7, 1 Hz, 3 H), 5.85 (dq, J ) 15, 7 Hz, 1 H), 6.2 (ddq, J )
15, 11, 1 Hz, 1 H), 6.4 (d, J ) 15.5 Hz, 1 H), 6.75 (dd, J )
15.5, 11 Hz, 1 H), 7.2-7.4 (m, 5 H). Z-45: 1H NMR (CDCl3)
δ 1.9 (dd, J ) 7, 1.8 Hz, 3 H), 5.6 (dq, J ) 10.5, 7 Hz, 1 H), 6.2
(ddq, J ) 11, 10.5, 1.8 Hz, 1 H), 6.5 (d, J ) 15.5 Hz, 1 H), 7.1
(dd, J ) 15.5, 11 Hz, 1 H), 7.2-7.4 (m, 5 H). E-46: 1H NMR
(CDCl3) δ 1.75 (d, J ) 6.5 Hz, 3 H), 5.85 (dq, J ) 15, 6.5 Hz,
1 H), 6.15 (t, J ) 11 Hz, 1 H), 6.25 (d, J ) 11 Hz, 1 H), 6.4-
6.75 (m, 1 H), 7.2-7.5 (m, 5 H). Z-46: 1H NMR (CDCl3) δ
1.85 (d, J ) 7 Hz, 3 H), 5.65 (dq, J ) 10, 7 Hz, 1 H), 6.4-6.6
(m, 3 H), 7.2-7.35 (m, 5 H). Low-resolution NMR spectra have
previously been reported for E-45 and E-46.36
Samples obtained from stereoselective syntheses served to
identify (E)-5-phenyl-2-pentene (E-41)30,31 and Z-41.31,32 Solu-
tions of the diazo compounds 40 in methanol were treated with
a few drops of methanolic HCl to give the ethers 43, which
were purified by HPLC (Si-60-5-C18, methanol-water ) 3:1).
5-Methoxy-5-phenyl-(E)-2-pentene (E-43): 1H NMR (CDCl3) δ
J O971691T
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